Flurandrenolide

This article is compiled based on the United States Pharmacopeia (USP) – 2025 Edition

Issued and maintained by the United States Pharmacopeial Convention (USP)

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C₂₄H₃₃FO₆       436.51

Pregn-4-ene-3,20-dione, 6-fluoro-11,21-dihydroxy-16,17-[(1- methylethylidene)bis(oxy)]-, 6α11β,16α)-.

6α-Fluoro-11β,16α,17,21-tetrahydroxypregn-4-ene-3,20-dione, cyclic 16,17-acetal with acetone CAS RN®: 1524-88-5; UNII: 8EUL29XUQT.

Flurandrenolide contains not less than 97.0 percent and not more than 102.0 percent of C₂₄H₃₃FO₆, calculated on the dried basis.

Packaging and storage—Preserve in tight containers in a cold place, protected from light.

USP Reference standards 〈11〉—

USP Flurandrenolide RS

Identification—

Change to read:

A: Spectroscopic Identication Tests 〈197〉, Infrared Spectroscopy: 197K (CN 1-May-2020) .

Change to read:

B: Spectroscopic Identication Tests 〈197〉, Ultraviolet-Visible Spectroscopy: 197U (CN 1-May-2020)

Solution: 20 µg per mL.

Medium: methanol.

Absorptivities at 237 nm, calculated on the dried basis, do not differ by more than 3.0%.

Specific rotation 〈781S〉: between +145° and +153°.

Test solution: 10 mg per mL, in chloroform.

Loss on drying 〈731〉—Dry it in vacuum at 105° for 4 hours: it loses not more than 1.0% of its weight.

Ordinary impurities 〈466〉—

Test solution: methanol.

Standard solution: methanol.

Application volume: 10 µL.

Eluant: a mixture of toluene and isopropyl alcohol (90:10), in a nonequilibrated chamber.

Visualization: 1.

Assay—

Mobile phase—Prepare a filtered and degassed mixture of methanol and water (60:40). Make adjustments if necessary (see System Suitability under Chromatography 〈621〉).

Internal standard solution—Dissolve Prednisone in Mobile phase, with the aid of sonication, to obtain a solution containing about 1 mg per mL. Standard preparation—Transfer about 5 mg of USP Flurandrenolide RS, accurately weighed, to a 10-mL volumetric ask, add 2.0 mL of Internal standard solution, dilute with Mobile phase to volume, sonicate to aid solution, and mix to obtain a solution having a known concentration of about 0.5 mg of USP Flurandrenolide RS per mL.

Assay preparation—Transfer about 5 mg of Flurandrenolide, accurately weighed, to a 10-mL volumetric ask, add 2.0 mL of Internal standard solution, dilute with Mobile phase to volume, sonicate to aid solution, and mix.

Chromatographic system (see Chromatography 〈621〉)—The liquid chromatograph is equipped with a 240-nm detector and a 4-mm × 25-cm column that contains packing L1. The ow rate is about 1 mL per minute. Chromatograph the Standard preparation, and record the peak responses as directed for Procedure: the order of elution is prednisone followed by flurandrenolide, the resolution; R, between the analyte and internal standard is not less than 2.0; and the relative standard deviation for replicate injections is not more than 3.0%.

Procedure—Separately inject equal volumes (about 20 µL) of the Standard preparation and the Assay preparation into the chromatograph, record the chromatograms, and measure the responses for the major peaks. The relative retention times are about 0.5 for prednisone and 1.0 for flurandrenolide. Calculate the quantity, in mg, of C₂₄H₃₃FO₆ in the portion of Flurandrenolide taken by the formula:

10C(R_U /R_S )

in which C is the concentration, in mg per mL, of USP Flurandrenolide RS in the Standard preparation; and R_U and R_S are the peak response ratios obtained from the Assay preparation and the Standard preparation, respectively.